United will debut the 787-10, which it configures with 318 seats including 44 of its updated business class product Polaris and 21 of its new premium economy product, on flights between Newark and Los Angeles on 7 January 2019. The aircraft will begin flying between Newark and San Francisco on 14 February 2019.

The airline plans to fly the 787 on six routes to Europe from Newark next summer, but has yet to disclose the markets.

The 787-10 is the embodiment of United's fleet strategy. A stretch-of-a-stretch, the aircraft carries 66 more seats than the comparable 787-9 with only a 1,205nm range penalty. This makes it an "economic powerhouse", as one airline executive once described it, well suited for shorter, high-density long-haul routes that do not need the range or capabilities of either the 787-8 or -9.

United says the 787-10 burns 20% less fuel than "older generation" aircraft, without specifying the older types.

The carrier has long been a champion of stretched aircraft with better seat economics, for example with its 2017 decision to convert 100 Boeing 737 Max 9 orders to the larger Max 10.

United, which has 14 787-10s on order, is the third operator of the aircraft after Singapore Airlines and Etihad Airways. It plans to take two more aircraft by the end of the year.

The airline does not have financing in place for any of its 787-10s. However, FlightGlobal understands that it plans a secured enhanced equipment trust certificate (EETC) transaction before the end of 2018 that could include the aircraft as collateral.

United operates 12 787-8s and 25 -9s, in addition to the -10 it took today, Flight Fleets Analyzer shows. It has orders for 13 787-9s, including nine that it ordered in October, and 13 -10s.